/*
 * Anything: A flexible and easy to use data structure that combines the 
 * characteristics of a list and a hashmap into one data structure.
 * 
 * Based on a paper by Peter Sommerlad and Marcel Rueedi on 
 * 'Do-it-yourself reflection' entered at EuroPLOP 1998.
 * 
 * This library was written completely from scratch and is based only 
 * in spirit on the original Java Anything implementation written by 
 * Andre Weinand/Marcel Rueedi in 1997/99 and enhanced by Stefan Tramm 
 * in 2006.
 * 
 * Copyright (c) 2008 Thomas Marti and others. All rights reserved.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package any.functor.impl.func;

import any.ImmutableAny;

/**
 * 
 * @param <TO> Type of the function output
 * @param <DS> Type for default/start value
 * @param <T>  Implementation type of the function
 */
public abstract class BaseDefaultableFunction<TO, DS, T extends BaseDefaultableFunction<TO, DS, T>> 
	extends BaseAnyFunction<TO, DS, T> {

	protected BaseDefaultableFunction() {
	}

	protected BaseDefaultableFunction(Class<TO> type) {
		super(type);
	}
	
	protected BaseDefaultableFunction(String description) {
		super(description);
	}

	protected BaseDefaultableFunction(Class<TO> type, String description) {
		super(type, description);
	}
	
	public TO apply(ImmutableAny from) {
		if (hasDefault) {
			return applyWithDefault(from, defaultValue);
		} else {
			return applyWithoutDefault(from);
		}
	}

	protected abstract TO applyWithoutDefault(ImmutableAny from) throws IllegalStateException;

	protected abstract TO applyWithDefault(ImmutableAny from, DS defaultValue);
	
	protected String toStringPrefix() {
		return description;
	}
	
	@Override
	public String toString() {
		String str = toStringPrefix();
		
		if (hasDefault) {
			str += " with default '" + defaultValue + "'";
		}
		
		return str;
	}
	
}
